1. Field of the Invention
The present invention relates generally to manual dollys. More specifically, the present invention relates to an aircraft dolly having particular utility for the manipulation of tail wheeled aircraft.
2. Description of the Related Art
There are known several manual dolly configurations suitable for general purpose use.
U.S. Pat. No. 4,505,489 to Specie discloses a dolly system for campgrounds and having particular utility for the moving of picnic tables and the like. An elongated handle member is journaled to each separate axle of a pair of spaced apart wheels. An elongated lifting member connected to the elongated handle extends forwardly of the wheels and contains a U-channeled brace thereon for fitting under the cross brace of a picnic table. The operator pushes down on the dolly in the conventional manner to lift the object to be moved and steers the dolly from a cross-bar linking two parallel spaced apart elongated handle members.
U.S. Pat. No. 3,799,582 to Courtright discloses a wheel cradle structure for use with agricultural irrigation lines. The Courtright reference is not a levered dolly system but shows a cradle capable of suspending a wheel off of the ground. The cradle is axially suspended between two wheels and may be connected in series with like cradles through linkage arms contained on either side of the cradle. The operative wheel support members of Courtright extend at right angles to the axles of the cradle wheels.
U.S. Pat. No. 3,456,960 to Rector discloses a two-wheeled hand cart having carrying tines which fold up against the hand cart frame. Lift for the object to be carried is supplied in the conventional manner by pushing down on the elongated handle members of the hand cart. The carrying tines of the Rector invention extend at right angles to the wheel axle.
U.S. Pat. No. 3,306,624 to Goss discloses a dolly for moving boxes of glass. The Goss invention discloses a carrying base which is tipped forwardly to fit under a lower edge of a glass piece and then force is applied downwardly on the handle to bring the glass sheet to the horizontal. The glass sheet is balanced between two elongated handle members serving as levers for the carrying base.
U.S. Pat. No. 1,241,418 to Mosher discloses a collapsible automobile dolly. Mosher discloses two roller wheels supported by a central axle. Disclosed on the central axle are support members for holding an automobile axle or axles off the ground. An elongated tilt bar extends from the central axle.
None of the above inventions disclose any utility for moving a wheeled craft such as a tail wheel airplane by surrounding a wheel thereof with lifting arms extending parallel to the axle from an elongated lever. Further, the disclosed dolly systems all rely on a downward force placed on the lever to lift the object to be moved thus placing strain on the back and shoulders and making steering of the object more difficult.
Also, in using a downward force, the operator's body weight is counterbalanced by the object lifted, thus tending to lift the operator, resulting in less traction between the operator and the ground. Such a traction loss can be inconvenient or even dangerous on loose surfaces, such as gravel, when the operator is "manually" operating a dolly.
There are known prior aircraft dollys operating in a manner similar to the known dollys, which require the operator to physically lift the aircraft onto the carrying platform of dolly. As there are often no convenient lift points or pushing surfaces located on an aircraft there exists the need to provide for a lifting dolly which can be placed around the aircraft wheel without manipulation of the aircraft itself, and thereby lift the wheel providing in effect a wheeled handle for manipulation of the aircraft by pushing or pulling. It is further desirable to provide such an aircraft dolly which derives its lifting force from a lifting of the lever as can be done with the strong leg muscles of the operator, as in proper lifting technique, thereby preventing body strain on the operator and making the aircraft easier to steer during manipulation thereof. The present invention provides a dolly system having these advantages and which is further capable of being easily stored. A dolly according to the present invention is constructed so as to minimize the possibility of the aircraft loosening itself from the constraints of the dolly.
There is also known a tail wheel aircraft tow bar. U.S. Pat. No. 4,659,124 discloses a hand carried tow bar for tailwheel aircraft having an elongated bar with clamping jaws at an end thereof. The jaws are clamped around a tail spring of the aircraft and the operator manipulates the aircraft by pulling, or less effectively, pushing, on a handle located at a second end of the bar. The tail spring of the aircraft must having a strongly vertical orientation and generous clearance beneath the aircraft tail for this tow bar to be effective. The clamping force of the jaws and subsequent manipulation of the aircraft through the tailspring might tend to cause premature metal fatigue in the tailspring. Turning of the aircraft using this tow bar requires great effort against the tail spring to force the craft against normal wheel friction instead of using the wheels to pivot the craft. The design of this tow bar also requires relatively elaborate machining and/or casting of its component parts. Use of this tow bar presents the possibility of injurious contact to the aircraft from the tow bar. Further, an individual tow bar of this type is not readily adaptable for use with a wide range of tail spring sizes.
Obviously then there exists a need for a tail wheel aircraft manipulator mechanism which eliminates these drawbacks in the current art. The present invention not only solves the aforementioned problems of the current art but is also readily adaptable for use with nose wheel aircraft.